1. Field of the Invention
The present invention relates to a method for testing a printed circuit board which comprises a plurality of networks composed of contact points and interconnects.
2. Description of the Prior Art
Electron beam measuring methods for testing the electrical properties of printed circuit boards and of miniaturized connecting modules are known from the publication Scanning Electron Microscopy, Vol. III, 1985, pp. 991-999, from the publication Microelectronics Engineering, Vol. 8, 1988, pp. reference. Modified scanning electron microscopes are usually employed for the implementation of these methods. Due to the deflection chromatic aberration and the aberrations of the objective lens that increase greatly with the deflection angle, their scanning fields, however, are limited, so that only printed circuit boards having a maximum size of approximately 10 cm.times.10 cm can be presently checked (Probe Diameter d.ltoreq.30 .mu.m). Efforts to enlarge the scanning field by improving the electron optics led to the development of low-error or low-aberration objective lenses having integrated deflection systems (see, for example, J. Vac. Sci. Techn., Vol. 19, No. 4, 1981, pp. 1014, 1018). The further development thereof, however, involves a high technological and financial expenditure.